Process of making nitrites.



PATBNTED NOV. 19, 1907. 0. SGHUNHERR & W. GAUS.

PROCESS OF MAKING NITRITES.

APPLICATION FILED 001216 1908.

WITNESSES: Si VEZTORS WAWJ Q'Q I 0&0 c an err' i2 flza'fiw gl lz elm Gaus ATTORNEY the second phase (resulting in the oxidation OTTO SOHONHERR AND WILHELM GAUS, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY,

ASSIGNORS TO BADISOHE ANILIN & SODA FABRIK, OF LUDWIGSHAFEN-ON-TI'IE RHINE, GERMANY, A CORPORATION.

PROCESS OF MAKING NITBITES.

To all whom it may concern:

Be it {known that we, OTTO Scnonnnnn and WInHELM GAUs, doctors of philosophy and chemists, subjects, respectively, of the King of Saxony and the King of Prussia, residing at Ludwigshafen-on-the-Rhine, Germany, have invented new and useful Improvements in the Process of Making Nitrites, of which the followingis a specification. i

It is well known that if nitric oxid (NO) be mixed with an excess of oxygen at ordinar temperature it becomes, after a time, comp etely oxidized to nitrogen tetroxid (N 0,, or NO,). Berthelot (see' Bulletin (16 la Soait Ohimt'que de Paris XXI, 1874,

page 100) stated that this oxidation takes place in two phases, the first phase (represented by the formula 4NO+O =2N O and resulting in the production of nitrogen trioxid) taking place very rapidly, 'Whereas of nitrogen trioxid to nitrogen tetroxid accordin to the formula 2N O +O,=2N O proceeds'comparatively sloWl I taschig has recently studied the quantitative course of this reaction (see Zeitschrift f'iir angewandte Ohemte, 1905, page 1281) and has come to the conclusion that it should be possible to produce nitrites quantitatively from the nitric oxid which is produced by causing electric discharges to-take place in atmospheric air, if the apparatus be so constructed that, within about one second after the nitric oxid be formed, the nitrogen trioxid, produced by its oxidation, be absorbed by the absorbing medium. Such a construction of apparatus is, of course, extremely difficult to carry out, especially on a practical scale for commercial production.

We have now discovered that in order to produce nitrites it is by no means necessary to absorb the nitric oxid so immediately after itsformation, but that pure nitrites can be obtained if the nitrous gases arising from nitric oxid, which consist, according to Raschig, of N 0 or according to other authors, of a mixture of NO and N O be maintained sufliciently hot until they are treated with the absorbing medium. Accordingly,- when producing nitrites from gases containing nitrogen trioxid, or nitric oxid and oxygen, or a mixture of nitrogen trioxid and nitric oxid and oxygen, the said gases are,

Specification of Letters Patent. Application filed October 16.1906. Serial No. 339,189.

Patented Nov. 19, 1907.

I according to our invention, until they are treated with the absorbing medium, maintained at a temperature at which no further oxidation, or practically no further oxidation, of the nitrogen trioxid takes place. A temperature of about three hundred (300) degrees centi rade is an advantageous temperature for this purpose.

For absorption purposes, when proceeding accordin to this invention, the hydroxids of the alkalies and of the alkaline earths, and also the alkali carbonates, are particularly suitable, but the invention is not limited to the use of such absorbents. When the hot gases are'passed into solutions of such compounds, however, a considerable quantity of steam is evolved and, in consequence, the gases become diluted. As the absorption takes place much more slowly when the gases are diluted, it is preferred to use, for absorbin purposes, a solution which gives rise to as little steam as possible. Hence the solution should be kept cold and have the lowest practicable vapor tension, for instance solutions which already contain considerable quantities of nitrite can be used.

Our invention is'particularly suitable for application to the gases which are produced by causing electric discharges to take place in the air, but it is applicable to any gases which contain nitrogen trioxid, or nitric oxid and oxygen, or a mixture of these, or which, upon treatment with air give rise to nitrogen trioxid and nitrogen tetroxid.

Since the date of this invention the controversy as to whether nitrogen trioxid exists in the gaseous condition has been revived. On the one hand it is pointed out that the gas having the composition re resented by the formula N 0 does not 0 ey Avo 'adros law, if that be its composition. On tile other hand, it is universally admitted alkaline absorbents as if it were the indi- "vidual N 0,. The foregoing s ecification is written taking the view that t e said gas is process described and claimed remains the same, whatever may be ultimately decided to be the chemical nature of the gasesdealt with.

The drawing accompanying this specification will help toillustrate the nature of our invention and a mode of carrying the same that this gas or mixture behaves towards nitrogen trioxid and not a mixture, but the into practical efi'ect, but we do not limit our lnvention to the method and apparatus shown in the said drawin which represents a vertical section through t e ap aratus;

An electrical current from t e generator G after having been transformed in the transformer T is used to produce a discharge between the insulated electrode 'E and .the electrode F which preferably forms art of the conducting vessel A in which the two electrodes are situated and Within whichthe. discharge takes place. At the same time air is passed through the vessel -A entering throughthe aperture H and the hot mixture of unaltered air and nitrous gases passes from the vessel A through the pipe B into the absorber D; The pi e B is jacketed with another pipe C after are manner ofa Liebig condenser and a current of hot fluid is passed between the two pipes Band C in order to prevent the gases passing through B from osing too much heat before they enter the absorbing mediumin'D'. The fluid which is passed through 0 depends on the temperature required and may consist of heated air, or ofa vapor of a liquid which boils at the desired temperature; for instance alpha-naphthylamin which boils at three hundred degrees centigrade (300 C) can be used if this tem erature be desired.

at we claim is: 1. The process of producing nitrites which consists in treating gases containing nitrogen trioxid with a hereinbefore defined absorbing medium and in maintaining the gases, until they are treated with the absorbing medium at a temperature at which practically no oxidation of the nitrogen tri- I oxid takes place. i

2, The process of producing'nitrites which consists in treating gases containing nitrogen trioxid with caustic soda solution and in maintaining the gases until they are treated ing witnesses.

OTTO SOHQNHERR. WILHELM GAUS. Witnesses:

J. ALEO. LLOYD, H. W. HARRIs, 

